Failure of a knee arthroplasty can be caused by a variety of factors, and such failure requires knee revision surgery. When a distal condylar defect is present during total knee replacement, the surgeon corrects this condition by preparing the defective bone to accept a femoral component implant that includes an augment. Typically, the distal end of the femur is resected to remove diseased or unhealthy bone to ensure sufficient anchoring and proper fit of the femoral component implant. Augments are used with the femoral component to increase the thickness of the inferior portion of the femoral component to compensate for lack of sufficient bone tissue. Thus, an augment is a spacer to fill a gap between the femoral component and the resected femur.
Trial components are used in knee replacement surgery to assist the surgeon in determining the appropriate size and type of femoral implant to use on a particular patient. A femoral trial is placed on a resected femoral surface and a tibial trial is placed on a prepared tibial surface. With the trials in place, the knee is checked for flexion and extension. Thus, during the trialing phase of the surgical procedure, the surgeon makes a final check of the reconstructed joint by temporarily inserting the trials, which mimic the final implants prior to permanent placement of the implant. Similar to the final implants, augments are used, particularly for the femoral trial, so that the surgeon can fill any voids and deficiencies between the inner surface of the trial and the resected femur.
Presently, trial augments having thicknesses between 2 mm and 20 mm are used with femoral trials. Typically, a set of trial augments are provided in a surgical tray having thicknesses of 5 mm and 10 mm, and in some cases, 5 mm, 10 mm, and 15 mm. In addition, the trial augments generally are provided in 8 different standard sizes that vary in length in the anterior-posterior direction and width in the medial-lateral direction to be used with various sized femoral trials. The distal femoral trial augments that are currently in use are specific to the size of the femoral trial component to be used. Since the final implant size selection is not made until the time of surgery, a large number of different sized trial augments have to be stored and available for use in a sterilized tray. It would be desirable to reduce the number of trial augments required for knee surgery.